In a wiper apparatus for wiping a windshield glass with a wiper blade, the wiper blade attached to a tip of a wiper arm is operated by a wiper motor that rotates upon reception of power from a vehicle battery. However, a surge in which a voltage suddenly increases may be generated in power supplied from a battery. The surge may become a voltage exceeding a withstand voltage of an element such as a capacitor and an integrated circuit constituting the circuit of the wiper apparatus. In such a case, the element constituting the circuit may be damaged.
Even when the surge occurs, if the motor is rotating, overvoltage due to the surge is spent by the rotation of the motor, and the risk of damage to the element constituting the circuit is reduced. However, since the wiper motor temporarily stops rotating at a position at which the wiper blade is inverted, there is a case in which the surge cannot be spent by the rotation of the motor, and the element constituting the circuit may be damaged by the high voltage.
The surge can be eliminated by adding a surge countermeasure Zener diode to the circuit. However, Zener diodes capable of coping with high voltage and large current are generally expensive, and there is a risk that the manufacturing cost of the product will be increased.
Japanese Patent Application Laid-Open (JP-A) No. 2015-205574 discloses a control for eliminating overvoltage due to a surge by energizing terminals of the winding of a motor so as to rotate a wiper motor (hereinafter abbreviated as a “motor”) forward and backward at minute intervals of m seconds.